Lithium Hydroxide → 5-(4-Trifluoromethyl-3-pyridyl)-1,2,4-oxadiazole-3-carboxylic acid

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반응 단계

15.8 g of 3-ethoxycarbonyl-5-(4-trifluoromethyl-3-pyridyl)-1,2,4-oxadiazole are initially charged in 13 ml of methanol, and, with ice-cooling at 0° C., a solution of 2.8 g of lithium hydroxide in 50 ml of water is added dropwise. The mixture is stirred at room temperature for 2 h, 20 ml of ice-water are added and the mixture is extracted with 200 ml of diethyl ether. The aqueous phase is adjused to pH=2 using dil. HCl, and the precipitated product is filtered off with suction. After drying, 13.8 g of 5-(4-trifluoromethyl-3-pyridyl)-1,2,4-oxadiazole-3-carboxylic acid are obtained as a white solid of mp. 157-159° C.

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